[RVRC] FW: Top secret???

[E Drew Moore]

Bryan, thanks. Whenever we increase our power above 100 watts two things
happen. 1.) We create intermod that effects the ETSNJ and the W2LI
repeaters, and 2.) we impact repeaters outside of our coordinated area. Both
create undesirable consequences. 

-----Original Message-----
From: rvrc-bounces at mailman.qth.net [mailto:rvrc-bounces at mailman.qth.net] On
Behalf Of Bryan D. Boyle
Sent: Saturday, April 16, 2011 3:56 PM
To: rvrc at mailman.qth.net
Subject: Re: [RVRC] Top secret???

On 4/16/2011 2:59 PM, njradioman at aol.com wrote:
> 
> I don't feel we need an amp that puts out 250 watts.
> 
> What do we want to do, start interfering with other repeaters, I don't
think so.
> 
> My vote is no .
> 
> Let's stay with a 100 to 150 watt model.
> 
> Marty

This will run, as Scott said, at 100 to 150w comfortably.

Advantages:

1. We can run it at less than its' full-bore rated power, it will
operate cooler and shed less heat.  That it's capable of doing 250 does
not mean that we necessarily SHOULD run it at 250.  The amp is capable
of running at less than it's fully rated power by design without spurs,
garbage, or harmonic and linear distortion of the signal. Henry tells
you how, and rates the amp for running at less than full output.

2. Less thermal stress on the components.  250w is a lot.  So is 150.
About a minimum of 40% less, though.

3. The amp is linear; less in (drop the exciter to 1w) and run at
reduced power.

4. The difference between running 100w and 250w in geographic range at
our HAAT is a lot less than the difference between 25 and 100.  The 625
machine gets down here in PA fine (a little scratchy) at 25W.  That's 35
air miles.  So, figure, @ 4x or more, the power increase will double
that. (I'm as far from the site as midtown manhattan, fwiw.)

5. The cost to purchase an at-the-limit 100w amp somewhere down the road
will be more than the cost to purchase this amp and have the factory
(which has a good rep, I mean, who wouldn't want, even today, an Henry
sitting on the floor in their shack...) recondition it.

6. The AC/DC power system was sized specifically to handle up to 40-45A
load through the powergate into the battery backup, assuming up to 150W
of transmitter/amp power.  The limiting factor will be how much power we
would want the amp to generate which will determines the resultant load.
 The power supplies are capable of providing 60A of current at 13.8V.
IF we are smart and not looking to throw blue flames and cook hot dogs
close to Eric's tower, then keeping the total DC power draw (see above)
under, let's say, 75% of the 45 amp capacity of the charge controllers
will give us more than enough range.  IF we don't try and run at
250w..the system will handle it just fine.

7. Stated current draw at 250w is 45 amps.  Current draw at 150 would
about 27 amps from my calculations, all things being equal.  The Icom,
running at 25W input, is drawing a little over 8 amps.  Dropping the
Icom down to 1W to tickle the amp to give us our desired output would
draw a little over 3.5-4 amps (some of the power is used for other
things besides transmit..have to drive the receiver and oscillator,
etc..).  I show that as a total of 30.5-31 amps @ 13.8v to drive to 150w
tpo into the duplexer.  Comfortably under the 75% of capacity of the
charge controller.

I don't see a downside to this.  Feel free to disagree, but this is my
analysis and conclusion.

73 Bryan
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